Life for veterans is consistently difficult because of post-traumatic stress.
This story does the interesting thing of showing Doc's point-of-view as a whirlwind of interconnected and tangential flashbacks, some about his life in America, some about his time in Japan, but all of them are intermingled, and a continuous dread runs through all of them, even though Doc is consistently pursuing a more peaceful life. As the novel goes on, we learn that this sporadic point of view is because he is constantly avoiding his traumatic memories about K, a rejected daughter who was sold to the army by her parents to be raped. Doc watched a terrible fate befall her, leaving him with PTSD, explaining the scattered point of view.
Misogyny is horrifying.
There has historically been a tremendous misogyny between armed forces and the women of the enemy culture, and historically, as depicted in the novel, this can often mean that women are the victim of brutal gang rapes during warfare. This horrifies Doc, leaving him with a burden for women that leads to his adoption of Sunny. But, in the end, it takes both of them working together for either of them to move beyond the horrors of life.
Bullets and bombs are not the only horrifying part of war.
Doc shows how WWII brought out the worst in people, so that even if you were safe from attack, more or less, horrifying and traumatic experiences were still around in plenty. Therefore, veterans are left with complex, difficult scars that make daily life nearly impossible some days. But Doc wants to be happy again, so he ends up reunited with his daughter regardless of how arduous that journey was.
PTSD can be triggered by almost anything, at random.
Although the book doesn't specifically state that it is about PTSD, it does show all the symptoms of the condition. Consider for example that Doc tells the story in flashbacks that are triggered by tangentially related occurrences from daily life. Doc is left vulnerable in this way, because random events can send him back into the most emotionally trying parts of his life.
